Cylinder blocks of two cycle crankcase compression engines are now commonly formed by die casting. For economic reasons, however, it has become desirable to form engine blocks by the lost foam process. Such a process allows the manufacturer to form a more complex cylinder block by first casting the foam pattern in several parts, then gluing the pattern parts together, to form the more complex pattern. The resulting cylinder block cast by such a pattern can have a more complex shape than could be achieved using the more conventional die casting process. Commonly, foam patterns duplicate the patterns for pre-existing components such as cylinder blocks, water jacket covers, and exhaust manifolds. The foam pattern components can then be glued together to eliminate machining and assembly operations which would have been required by the prior die casting processes. The foam pattern components are typically formed by die casting, so that it is a natural step to provide foam pattern components in a form similar to that used for the die cast aluminum components. An example of one such prior die cast engine block using multiple components to ahieve the desirable flow passage shapes is shown in U.S. Pat. No. 4,328,770 to Hale.